U.S. patent number 7,229,570 [Application Number 10/616,914] was granted by the patent office on 2007-06-12 for slurry for chemical mechanical polishing.
This patent grant is currently assigned to NEC Electronics Corporation. Invention is credited to Kenichi Aoyagi, Tomoyuki Ito, Shin Sakurai, Toshiji Taiji, Yasuaki Tsuchiya.
United States Patent |
7,229,570 |
Taiji , et al. |
June 12, 2007 |
**Please see images for:
( Certificate of Correction ) ** |
Slurry for chemical mechanical polishing
Abstract
The present invention relates to a slurry for chemical
mechanical polishing, which contains a silica polishing material,
an oxidizing agent, a benzotriazole-based compound, a diketone and
water.
Inventors: |
Taiji; Toshiji (Kanagawa,
JP), Tsuchiya; Yasuaki (Kanagawa, JP), Ito;
Tomoyuki (Tokyo, JP), Aoyagi; Kenichi (Tokyo,
JP), Sakurai; Shin (Tokyo, JP) |
Assignee: |
NEC Electronics Corporation
(Kanagawa, JP)
|
Family
ID: |
31185066 |
Appl.
No.: |
10/616,914 |
Filed: |
July 11, 2003 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20040021125 A1 |
Feb 5, 2004 |
|
Foreign Application Priority Data
|
|
|
|
|
Aug 2, 2002 [JP] |
|
|
2002-226103 |
|
Current U.S.
Class: |
252/79.1;
438/692; 252/79.4 |
Current CPC
Class: |
C09G
1/02 (20130101) |
Current International
Class: |
C09K
13/00 (20060101); C09K 13/06 (20060101); H01L
21/302 (20060101) |
Field of
Search: |
;252/79.1,79.4
;438/692 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
7-233485 |
|
Sep 1995 |
|
JP |
|
8-83780 |
|
Mar 1996 |
|
JP |
|
10-116804 |
|
May 1998 |
|
JP |
|
11-238709 |
|
Aug 1999 |
|
JP |
|
2000-133621 |
|
May 2000 |
|
JP |
|
2001-187876 |
|
Jul 2001 |
|
JP |
|
2001-187878 |
|
Jul 2001 |
|
JP |
|
2001-189296 |
|
Jul 2001 |
|
JP |
|
2002-164308 |
|
Jun 2002 |
|
JP |
|
2002-164309 |
|
Jun 2002 |
|
JP |
|
2002-164310 |
|
Jun 2002 |
|
JP |
|
2001-20384 |
|
Mar 2001 |
|
KR |
|
WO 98/49723 |
|
Nov 1998 |
|
WO |
|
Primary Examiner: Norton; Nadine G.
Assistant Examiner: Umez-Eronini; Lynette T.
Attorney, Agent or Firm: Young & Thompson
Claims
What is claimed is:
1. A slurry for chemical mechanical polishing, which comprises a
silica polishing material, an oxidizing agent, a
benzotriazole-based compound, a diketone and water, and wherein
said diketone is at least one type of a compound selected from the
group consisting of 1,2-diketones, 1,3-diketones and 1,4-diketones,
and wherein a content weight ratio of said diketone to said
benzotriazole-based compound (diketone/benzotriazole-based
compound) is not less than 0.05 but not greater than 50.
2. A slurry for chemical mechanical polishing according to claim 1,
wherein a value of a pH is in a range of 1 to 7.
3. A slurry for chemical mechanical polishing according to claim 1,
wherein said silica polishing material is colloidal silica.
4. The slurry for chemical mechanical polishing according to claim
1, wherein a content weight ratio of said diketone to said
benzotriazole-based compound (diketone/benzotriazole-based
compound) is not less than 0.1 but not greater than 10.
5. The slurry for chemical mechanical polishing according to claim
1, wherein the content of the silica polishing material is not less
than 1 wt %.
6. The slurry for chemical mechanical polishing according to claim
1, wherein the content of the silica polishing material is not less
than 1 wt % but not greater than 10 wt %.
7. The slurry for chemical mechanical polishing according to claim
1, wherein the content of the benzotriazole-based compound is not
less than 0.001 wt % but not greater than 0.5 wt %.
8. The slurry for chemical mechanical polishing according to claim
1, wherein the content of the diketone is not less than 0.001 wt %
but not greater than 5 wt %.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a slurry for chemical mechanical
polishing and more particularly a polishing slurry that is well
suited to a chemical mechanical polishing performed in the step of
forming a copper-based metal interconnection of a semiconductor
device.
2. Description of the Related Art
In the formation of a semiconductor integrated circuit such as an
ULSI, for which the progress to attain further miniaturization and
more densely spaced arrangement has been currently gathering more
speed, copper is a particularly useful material for electrical
connection to obtain the interconnection of good performance and
high reliability, because of its considerably low electrical
resistance and high resistance against the electromigration and the
stress migration.
Since it is difficult to work copper into shape by means of dry
etching, a copper interconnection is formed by so-called damascene
method, for instance, in the following way.
Firstly, a sunken section such as a trench or a connection hole is
formed in an insulating film formed on a silicon substrate. Next,
after a barrier metal film is formed on the surface inclusive of
the inside of this sunken section, a copper film is grown by the
plating method so as to fill up this sunken section. Polishing is
then carried out by the chemical mechanical polishing (referred to
as "CMP" hereinafter) method until the surface of the insulating
film other than the sunken section is completely exposed, so that
the surface may be planarized. Thereby, the formation of an
electrical connection section such as a buried copper
interconnection, a via plug or a contact plug, in which copper is
laid to fill up the sunken section, with a barrier metal film being
interposed therebetween, is accomplished.
When a buried-type electrical connection section is formed, a
barrier metal film is generally formed, as described above, for the
purpose of preventing the copper-based metal from diffusing into
the insulating film and improving the adhesion between the
copper-based metal and the substrate (the insulating film). For the
barrier metal film against copper-based metal, tantalum-based metal
such as Ta or TaN is favourably used.
To conduct the polishing of a copper-based metal film overlying
such a barrier metal film, it is necessary to take the differences
in polishing rate between the copper-based metal film and the
barrier metal film and that and the insulating film into
consideration.
Now, from necessity of filling up the sunken section of the
insulating film, the copper-based metal film must be formed
thickly. In order to polish and remove such a thick copper-based
metal film efficiently, a polishing slurry capable to make the
rapid polishing of the copper-based metal film is normally
utilized. However, when such a polishing slurry is used for the
barrier metal film made of a different material, the polishing rate
for this film generally becomes rather low. Therefore, if the
barrier metal film is made to be polished and removed thoroughly,
even the copper-based metal laid within the sunken section may be
excessively removed to create dishing. The phenomenon of this sort
is particularly notable when the tantalum-based metal is utilized
for the barrier metal film.
Accordingly, in order to prevent dishing of this sort from
occurring, there has been proposed the two-steps polishing method
which comprises the step of a first polishing wherein mainly a
thick copper-based metal film for filling is polished and removed,
and the step of a second polishing wherein mainly a barrier metal
film is polished and removed (for example, in Japanese Patent
Application Laid-open No. 189296/2001).
What is required in the step of the first polishing is that the
thick metal film for filling is polished and removed efficiently
therein, and the presence of the dishing thereafter is well
suppressed. Meanwhile, what is required in the step of the second
polishing is that, together with some metal for filling that may
remain after the step of the first polishing, the barrier metal
film is polished efficiently, using the insulating film as a
stopper, so that the polished face may be well planarized.
In such a two-steps polishing method, a CMP slurry having rather a
strong mechanical effect than a chemical one is generally employed,
in the step of the second polishing wherein mainly a barrier metal
film is polished and removed, because the hardness of the barrier
metal film is higher than that of the copper-based metal film.
However, if a polishing slurry whose mechanical polishing effect is
strong enough to attain a satisfactory polishing rate is used, the
insulating film may be excessively polished or its polished face
may become rough and, thus, a good electrical connection section
becomes hard to be formed. On the other hand, if a polishing slurry
whose pH is adjusted to be on the acidic side is used to achieve a
high polishing rate for the barrier metal film, its chemical
polishing effect becomes stronger and the polishing rate for the
copper-based metal for filling, higher, which may result in the
creation of dishing and poor planarity of the polished face.
As a conventional method of suppressing dishing, there has been
known a method wherein, through the use of a polishing slurry
containing benzotriazole or its derivative, a protective film is
formed on the surface of the copper film to prevent the ionization
of copper by the oxidizing agent and thereby chemical dissolution
of copper is suppressed. For instance, in Japanese Patent
Application Laid-open No. 83780/1996, it is described that dishing
of a copper film in the step of a CMP can be prevented by adding
benzotriazole or its derivative into a polishing slurry.
Nevertheless, with a conventional polishing slurry which contains a
protective-film forming agent such as benzotriazole, its effect of
coating the copper film through formation of the protective film
alone has a limitation, and its control over the polishing of the
copper film is rather restricted. Especially in the step of the
second polishing of the afore-mentioned two-steps polishing method,
the polishing rate for the copper film must be lowered much further
to improve the planarity of the polished face.
SUMMARY OF THE INVENTION
In light of the above problems, an object of the present invention
is to provide a chemical mechanical polishing slurry which can
polish and remove a barrier metal film at a satisfactory polishing
rate and, at the same time, can keep a polishing rate for a
copper-based metal film for filling low and, consequently, can
reduce the occurrence of dishing with effect.
The present invention relates to a slurry for chemical mechanical
polishing, which comprises a silica polishing material, an
oxidizing agent, a benzotriazole-based compound, a diketone and
water.
The present invention can polish and remove a barrier metal film at
a satisfactory polishing rate and, at the same time, can keep a
polishing rate for a copper-based metal film for filling low and,
consequently, can reduce the occurrence of dishing with effect.
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of the present invention are described
below.
A CMP slurry of the present invention contains a silica polishing
material (polishing grains), an oxidizing agent, a
benzotriazole-based compound, a diketone and water.
For a polishing material in the present invention, a silica
polishing material such as colloidal silica or fumed silica is
utilized, viewed from the points of the control over the polishing
of the copper-based metal film, the reduction of scratches on the
polished face and the dispersion stability of the slurry, and,
among them, colloidal silica is particularly preferable.
In respects of the polishing rate, the polishing accuracy, the
dispersion stability, the surface roughness of the polished face
and the like, the average particle size of the silica polishing
material, measured by the light scattering diffraction method, is
preferably not less than 5 nm, more preferably not less than 10 nm
and still more preferably not less than 20 nm, but preferably not
greater than 300 nm, more preferably not greater than 100 nm and
still more preferably not greater than 80 nm.
A content of the silica polishing material to the total amount of
the polishing slurry in the polishing slurry is appropriately set
within a range of 0.1 to 50 wt %, taking the polishing efficiency,
the polishing accuracy and the like into consideration. In
particular, from the viewpoints of the polishing rate, the
dispersion stability, the surface roughness of the polished face
and the like, it is set preferably not less than 0.5 wt % and more
preferably not less than 1 wt %, but preferably not greater than 10
wt % and more preferably not greater than 5 wt %.
An oxidizing agent in the present invention may be appropriately
selected from well known water-soluble oxidizing agents, taking the
polishing efficiency, the polishing accuracy and the like into
consideration. For example, there can be given peroxides such as
H.sub.2O.sub.2, Na.sub.2O.sub.2, Ba.sub.2O.sub.2 and
(C.sub.6H.sub.5C).sub.2O.sub.2; hypochlorous acid (HClO);
perchloric acid; nitric acid; ozone water; peracetic acid;
nitrobenzene and organic peroxides (ketoneperoxides,
diacylperoxides, hydroperoxides, alkylperoxides, peroxyketals,
alkylperesters, peroxycarbonates, water-soluble peroxides and
such). Among these, hydrogen peroxide (H.sub.2O.sub.2) is
preferable because it does not contain a metal component or does
not generate a harmful byproduct.
A content of the oxidizing agent to the total amount of the
polishing slurry in the polishing slurry of the present invention
is appropriately set within a range of 0.01 to 10 wt %, taking the
polishing efficiency, the polishing accuracy and the like into
consideration. The content thereof is set preferably not less than
0.05 wt % and more preferably not less than 0.1 wt % to achieve a
better polishing rate; but preferably not greater than 5 wt % and
more preferably not greater than 3 wt % to suppress the dishing and
regulate the polishing rate. When the content of the oxidizing
agent is too low, the chemical effects of the polishing slurry
become small so that the polishing rate obtained may become
insufficient or the damage may become liable to appear on the
polished face. On the other hand, when the content of the oxidizing
agent is too high, its etching capability (chemical effect) against
the copper-based metal increases and the dishing may become liable
to occur.
In the case that hydrogen peroxide is utilized as an oxidizing
agent, an excellent polishing slurry can be obtained by adding, for
example, an aqueous solution of hydrogen peroxide with a
concentration of 30 wt % to a concentration of 1 to 5 wt % in the
slurry (H.sub.2O.sub.2 concentration: 0.3 to 1.5 wt %). When such
an oxidizing agent relatively susceptible to deterioration with age
as hydrogen peroxide is used, it is possible to make separate
preparations of a solution containing, along with a stabilizer and
the like, an oxidizing agent at a given concentration and a
composition which is to produce a prescribed polishing slurry on
addition of the above solution containing the oxidizing agent, and
mix them together just before use.
The benzotriazole-based compound in the present invention can
prevent the copper-based metal from eluting out by forming a
coating film on the surface of the copper film, and thereby
contribute to the suppression of excessive polishing of the
copper-based metal. Moreover, if this compound is utilized together
with a diketone, which is described below, the excessive polishing
of the copper-based metal can be reduced even more and, thus, the
dishing is suppressed still further than that when the
benzotriazole-based compound is singly utilized.
Examples of such a benzotriazole-based compound, that is,
benzotriazole or its derivative, include benzotriazole without
substitution and substituted benzotriazoles such as
1-hydroxybenzotriazole, 4-hydroxybenzotriazole,
2,3-dicarboxybenzotriazole, 2,3-dicarboxypropylbenzotriazole,
4-carboxyl-1H-benzotriazole, 4-methoxycarbonyl-1H-benzotriazole,
4-butoxycarbonyl-1H-benzotriazole and methyl-1H-benzotriazole.
A content of the benzotriazole-based compound in the polishing
slurry of the present invention is set preferably not less than
0.001 wt %, more preferably not less than 0.005 wt % and still more
preferably not less than 0.01 wt %, but preferably not greater than
0.5 wt %, more preferably not greater than 0.2 wt % and still more
preferably not greater than 0.1 wt %. When the content of the
benzotriazole-based compound is too low, its effect of reducing the
excessive polishing of the copper-based metal becomes small. On the
other hand, even if the content of the benzotriazole-based compound
is set higher than necessary, the reducing effect matching with
that content cannot be obtained.
A diketone in the present invention can reduce the excessive
polishing of the copper-based metal even more when used together
with the afore-mentioned benzotriazole compound than when used
singly.
Examples of such a diketone include 1,2-diketones such as diacetyl,
acetylbenzoyl and benzyl; 1,3-diketones such as acetylacetone,
benzoylacetone and dibenzoylmethane; 1,4-diketones such as
furoylacetone, acetonylacetone and phenacylacetone and
1,5-diketones such as 2,6-heptadione. Any one of these diketones
can be used singly or, alternatively, two or more types of them can
be used together. Among these, at least one type of a compound
selected from the group consisting of 1,2-diketones, 1,3-diketones
and 1,4-diketones is preferable because it can suppress the
excessive polishing of the copper-based metal more
satisfactorily.
A content of the diketone in the polishing slurry of the present
invention is set preferably not less than 0.001 wt %, more
preferably not less than 0.005 wt % and still more preferably not
less than 0.01 wt %, but preferably not greater than 5 wt %, more
preferably not greater than 1 wt % and still more preferably not
greater than 0.5 wt %. A content ratio of the diketone to the
afore-mentioned benzotriazole-based compound
(diketone/benzotriazole-based compound) is preferably not less than
0.05 and more preferably not less than 0.1, but preferably not
greater than 50 and more preferably not greater than 10. When the
content of the diketone is too low, its effect of reducing the
excessive polishing of the copper-based metal becomes small. On the
other hand, even if the content of the diketone is set higher than
necessary, the reducing effect matching with that content cannot be
obtained.
A pH value of the CMP slurry of the present invention is set to be
preferably in a range of pH 1 to 7, more preferably in a range of
pH 2 to 5 and still more preferably in a range of pH 2 to 4. By
employing a CMP slurry whose pH is in such a range, it is possible
to carry out the polishing wherein the excessive polishing of the
copper-based metal film is well suppressed, while the polishing
rate for the barrier metal is kept high.
The pH of the CMP slurry may be adjusted by any well-known method,
and examples of an alkali which may be used therein include alkali
metal hydroxides such as sodium hydroxide and potassium hydroxide;
alkali metal carbonates such as sodium carbonate and potassium
carbonate; ammonia; and amines. Among them, ammonia or an amine
which contains no metal component is preferable.
The CMP slurry of the present invention may contain an acidic
compound when needed. The acidic compound can enhance the oxidation
effect brought about by the oxidizing agent, and besides, through
the control of its content, it can facilitate the adjustment of the
polishing rate for the copper-based metal as well as the pH
regulation and the pH stabilization. A content of the acidic
compound in the CMP slurry is set appropriately within a range of 0
to 5 wt %, preferably in a range of 0.005 to 2 wt % and more
preferably in a range of 0.01 to 1 wt %. When the content of the
acidic compound is too low, its addition does not produce
sufficient effects. On the other hand, when its content is too
high, the polishing rate for the copper-based metal film may
become, in some cases, unnecessarily high.
For the acidic compound described above, any one of organic acids
such as carboxylic acids and amino acids as well as various
inorganic acids can be employed.
As carboxylic acids, there can be given, for instance, oxalic acid,
malonic acid, tartaric acid, malic acid, glutaric acid, citric
acid, maleic acid, formic acid, acetic acid, propionic acid,
butyric acid, valeric acid, acrylic acid, lactic acid, succinic
acid, nicotinic acid and their salts.
As amino acids, there can be given, for instance, arginine,
arginine hydrochloride, arginine picrate, arginine flavianate,
lysine, lysine hydrochloride, lysine dihydrochloride, lysine
picrate, histidine, histidine hydrochloride, histidine
dihydrochloride, glutamic acid, sodium glutaminate monohydrate,
glutamine, glutathione, glycylglycine, alanine, .beta.-alanine,
.gamma.-aminobutyric acid, .epsilon.-aminocarproic acid, aspartic
acid, aspartic acid monohydrate, potassium aspartate, calcium
aspartate trihydrate, tryptophan, threonine, glycine, cysteine,
cysteine hydrochloride monohydrate, oxyproline, isoleucine,
leucine, methionine, ornithine hydrochloride, phenylalanine,
phenylglycine, proline, serine, tyrosine and valine.
As inorganic acids, there can be given, for instance, nitric acid,
nitrous acid, sulfuric acid, sulfurous acid, persulfuric acid,
boric acid, perboric acid, phosphoric acid, phosphorous acid,
hypophosphorous acid and silicic acid.
The CMP slurry of the present invention may contain a variety of
additives such as a dispersing agent, a buffer agent and a
viscosity modifier, which are in wide use as common additives to
the polishing slurry, provided that they do not affect adversely
the properties of the slurry.
For a method of preparing the CMP polishing slurry of the present
invention, an ordinary method of preparing an aqueous polishing
slurry composition with free grains can be applied. Specifically,
an appropriate amount of a polishing material is added to an
aqueous solvent and then, if necessary, with an appropriate amount
of a dispersing agent being added, a treatment of dispersion is
carried out. In the step of the dispersion, for example, an
ultrasonic disperser, a bead mill disperser, a kneader disperser, a
ball mill disperser or the like may be used, according to the
circumstances.
The CMP using a CMP slurry of the present invention may be, for
example, conducted in the following way. Firstly, there is provided
a substrate, wherein an insulating film is formed and a sunken
section in prescribed pattern shape is formed in the insulating
film and, thereon, a copper-based metal film is grown. This
substrate is placed on a wafer carrier such as a spindle. With a
prescribed pressure applied, the surface of this copper-based metal
film in this substrate is made to contact with a polishing pad
which is adhered onto a surface plate such as a rotary plate, and
while supplying a polishing slurry between the substrate and the
polishing pad, the wafer and the polishing pad are moved relative
to each other (for instance, both of them are rotated) and thereby
the wafer is polished. The polishing slurry may be supplied onto
the polishing pad from a supply tube set separately or it may be
supplied onto the surface of the polishing pad from the side of the
surface plate. If necessary, a pad conditioner may be brought into
contact with the surface of the polishing pad to condition the
surface of the polishing pad.
The CMP slurry of the present invention described above can be
applied with effect to a polishing treatment wherein a sunken
section such as a trench or a connection hole is formed in an
insulating film laid on a substrate, and by polishing, by the CMP
method, a copper-based metal film which is formed over the entire
surface thereof so as to fill up this sunken section with a barrier
metal film lying therebetween, an electrical connection section
such as a buried interconnection, a via plug, a contact is formed.
As an insulating film, there can be given a silicon oxide film, a
BPSG (Boro-Phospho-Silicate Glass) film, a SOG (Spin-on-Glass)
film, a SiOF film, a HSQ (Hydrogen Silses-Quioxane) film, a SiOC
film, a MSQ (Methyl-Silses-Quioxane) film, a polyimide film, a
Parylene.RTM. film (polyparaxylylene film), a Teflon.RTM. film and
an amorphous carbon film. As a barrier metal film well suited to
the copper-based metal film, that is, the copper film or the copper
alloy film whose main component is copper, there can be given a
tantalum-based metal film made of tantalum (Ta), tantalum nitride,
tantalum silicon nitride or the like.
In the afore-mentioned polishing treatment, a CMP slurry of the
present invention can be applied with best effect to the step which
starts with polishing of the barrier metal and, with the barrier
metal other than the sunken section being polished and removed,
ends in formation of an electrical connection section. For example,
in the two-steps polishing method described above, the step of the
second polishing is well suited for its application.
EXAMPLES
With reference to Examples, the present invention is further
described in detail below.
CMP Conditions
The CMP was carried out using a polisher SH-24 made by SpeedFam
Co., Ltd. The polisher was used, onto a surface plate of which a
polishing pad (IC 1400, made by Rodel Nitta Company) with a
diameter of 61 cm was attached. Polishing conditions were as
follows; a contact pressure of the polishing pad: 27.6 kPa, a
polishing area of the polishing pad: 1820 cm.sup.2, a rotating
speed of the surface plate: 80 rpm; a carrier rotating speed: 80
rpm; and a feeding rate of the slurry polishing agent: 100
ml/min.
As a substrate for polishing, a substrate in which a copper film or
a tantalum film was grown on a Si substrate by the sputtering
method was used.
Measurement of Polishing Rate
The polishing rate was calculated from the surface resistivities
before and after the polishing in the following way. Four needle
electrodes were aligned on the wafer with a given interval, and
with a given current being applied between two outer probes, a
potential difference between two inner probes was measured to
determine a resistance (R'), and further a surface resistivity
(.rho.s') was obtained by multiplying that value by a correction
factor RCF (Resistivity Correction Factor). A surface resistivity
(.rho.s) for another wafer film with a known thickness (T) (nm) was
also obtained. Since the surface resistivity is inversely
proportional to the thickness, if a thickness for the wafer with
the surface resistivity of .rho.s' is taken as d, an equation
d(nm)=(.rho.s.times.T)/.rho.s' is given. Using this equation, the
thickness d can be determined, and the polishing rate was then
estimated by dividing the difference between film thicknesses
before and after the polishing by the polishing time. For the
measurements of the surface resistivity, a surface resistance
detector (Four Probe Resistance Detector, Loresta-GP, made by
Mitsubishi Chemical Corporation) was used. Preparation of CMP
Polishing Slurry and Results of Evaluation
A number of slurries each of which contained 2 wt % of colloidal
silica (TSOL Series, made by Tama Chemicals Co., Ltd.; primary
particle size: approximately 50 nm), 0.02 wt % of benzotriazole
shown in Table 1 as a protective-film forming agent, 0.05 wt % of
diketone shown in Table 1, 1 wt % of an aqueous solution of 30 wt %
hydrogen peroxide (made by Kanto Kagaku), 0.02 wt % of oxalic acid
and water were prepared. Herein, for 1,2-diketone, 1,3-diketone and
1,4-diketone in Table 1, diacetyl, acetylacetone and acetonylaceton
were employed, respectively.
As Cases for Comparison, there were prepared slurries containing
either a protective-film forming agent or a diketone but not both
and a slurry containing a monoketone (ethylmethylketone) in place
of a diketone. A slurry which contains, as a protective-film
forming agent, 0.1 wt % of a triazole-based compound, instead of a
benzotriazole-based compound, was also prepared.
The pH value in each slurry of Examples and Cases for Comparison
was adjusted to be 3.5 with an aqueous solution of ammonia.
Using each one of slurries as prepared above, CMPs were carried
out. The results of measurements of the polishing rates for copper
(Cu) and tantalum (Ta) in those CMPs are listed in Table 1.
As the results in Table 1 clearly indicate, slurries (Slurry No. 1
to 4) containing both a benzotriazole-based compound and a diketone
can reduce the polishing rate for copper far more than any other
slurries. In the CMP with any one of these slurries, because the
polishing rate for the tantalum film (barrier metal film) does not
differ much, a ratio of the polishing rate of copper to that of the
barrier metal film is, hereat, small. In effect, these polishing
slurries successfully serve the purpose of planarizing the polished
face. It is, further, shown that the slurry (No. 2) containing
1,3-diketone and benzotriazole, in particular, is highly
effective.
TABLE-US-00001 TABLE 1 Cu Ta polishing polishing Slurry
Protective-film rate rate No. forming agent Diketone (nm/min)
(nm/min) 1 Benzotriazole 1, 2-diketone 71 71 2 Benzotriazole 1,
3-diketone 58 73 3 Benzotriazole 1, 4-diketone 73 76 4
Methylbenzotriazole 1, 3-diketone 70 -- 5 Benzotriazole -- 90 75 6
-- 1, 3-diketone 103 -- 7 1,2,4-1H-triazole 1, 3-diketone 110 -- 8
3-aminotriazole 1, 3-diketone 144 -- 9 Benzotriazole Monoketone 90
--
* * * * *